Respirator cartridge end-of-service lift indicator system and method of making

Abstract

Providing visual means for indicating when vapor/gas respirator cartridges have exhausted their capacity to provide respiratory protection at or below a hazardous concentration level. In combination with a vapor/gas indicator adapted to undergo a change in color with contact by an organic vapor or gas, there is provided a catalytic agent for enhancing activation and reaction of the indicator agent.

We claim: 
     
       1. In a respirator cartridge having a shell within which there is supported a gas/vapor sorbent and an indicator agent selected from the group consisting of sodium dichromate and potassium dichromate characterized to undergo a change in color concomitant with exposure to concentrations of organic vapors and gases which are below a threshold limit known to be safe to inhale, the improvement comprising: catalytic/oxidizing means for rendering a gas/vapor entering the cartridge and passing through said means more readily detected by said indicator agent than with non-use of said means, said catalytic/oxidizing means being located adjacent to an upstream of said indicator agent in said cartridge.   
     
     
       2. The improvement according to claim 1 wherein said catalytic/oxidizing means includes a carrier. 
     
     
       3. The improvement according to claim 2 wherein said carrier is activated carbon. 
     
     
       4. The improvement according to claim 2 wherein said carrier is silica gel. 
     
     
       5. The improvement according to claim 1 wherein said catalytic/oxidizing means is formulated of the approximate related proportions of ingredients of 50 grams activated carbon to which is added an impregnating solution of 200 ml H 2  O, 30 (±20) grams Na 2  Cr 2  O 7  and 30 (+30, -15) ml concentrated H 2  SO 4  ; said solution being reduced by said carbon and excess thereof decanted from said carbon with the residue allowed to dry in place as said catalytic/oxidizing means.   
     
     
       6. The improvement according to claim 5 wherein said decanted reduced sodium dichromate solution is applied to granular silica gel and dried thereinplace to provide said catalytic/oxidizing means.